Taxpayers must pay their taxes. In case the taxpayer takes evasive actions in order to avoiding this payment, tax authorities may use other mechanisms to enforce the payment of the taxes. This thesis deals strictly with tax warrants that allow tax authorities to take steps to collect the taxpayers’ debt. This thesis focuses on the warrants regulated in Spanish statutory tax laws. Personal tax warrants, as regulated in Spanish tax law, are particularly controversial. Many of the cases in which someone has to pay the tax debts when the taxpayer does not do this are wrongly regulated as personal warrants. As it is maintained in this thesis, some of these cases should be rather regulated as legal tax infringements than as personal warrants. Finally, the thesis addresses "voluntary" warrants, which presentation is mandatory but the taxpayer can freely choose among the different types that the law presents.